Solar cells have become a widely used technology to convert light energy to electrical energy. An array of solar cells can be interconnected and assembled into a solar module or a solar panel to achieve aggregated current and voltage generated by the individual solar cells. One prevalent approach of interconnecting solar cells is to overlap two solar cells to realize electrical connection, e.g., an upper cell and a lower cell. In a typical solar cell configuration, the back electrode of an upper cell is electrically connected with the front electrode of a lower cell. In this manner, multiple solar cells are interconnected in series.
More specifically, metal contacts disposed on the front and the back sides of a photovoltaic (PV) layer of a solar cell form the front electrode and the back electrode, respectively. The back electrode is disposed between the PV layer and a non-conductive substrate layer. Thus, when two cells partially overlap each other, the non-conductive substrate is disposed between the back electrode of the upper cell and the front electrode of the lower cell. To provide electrical continuity between the two overlapping cells, vias are made on the substrate and filled with a conductive material, which is commonly in the form of resin, paste or ink during the filling process and hardens after a cure process.
In practice, a back via is usually subject to overfill with the conductive material to prevent the formation of a void inside the via which can potentially lead to a failed contact. However, filling a back via with excess conductive material tends to cause an uncontrolled lateral overflow (or smear) of the conductive material from the via, especially when the two solar cells are stacked and pressed together for integration. The conductive material overflow can undesirably reach and bridge the front and back electrodes of another solar cell (e.g., the lower solar cell) and cause short circuit.
Conventionally, to solve this issue, an insulating material is deposited around the perimeter of the solar cells followed by a cure procedure. An insulating adhesive can be applied such that to both bond the overlapping solar cells for the mechanical integrity of the solar module, and to prevent the conductive material overflow described above from forming short circuit.
Further, series of the solar cells of a solar module needs protection from the mismatch in the properties of the interconnected solar cells such that energy generating capability of the interconnected solar cells will not be dissipated. When solar cells are arranged in an overlapping structure, one way is to connect a diode, also referred to as bypass diode, to a group of solar cells of the solar module by disposing a ribbon conductor at a position corresponding to the number of solar cells. The ribbon conductor provides an electrical contact between a contact terminal of the diode and a contact terminal of the series of the solar cells to bypass.
Therefore, there exists a need to eliminate the overlapping between solar cells and the associated insulation of the individual solar cells, to reduce the overall thickness of the solar panel caused by the overlapping of solar cells and the associated insulation, to conveniently connect diodes with series of solar cells of a solar module.